In recent years, a master video monitoring system having cameras, sensors, storage, etc., installed for preventing a crime has become drastically widespread with an increase in crimes represented by picking, a robbery, arson, etc. A system for performing wide-area monitoring and long-hour recording of several hundred points has also increased with adopting of IP (Internet Protocol) for a surveillance camera and a larger capacity of storage of a hard disk drive, etc. Under such circumstances, there is a demand for a technique for efficiently investigating a specific person of a shoplifter, a lost person, a person losing an article, etc., for lightening work of a guardian.
A method of previously storing feature data (faces, colors, shapes, etc.,) of an unspecified number of the general public extracted from camera images in a database and extracting and displaying a person matching the feature data of the person to be retrieved from the database exists as a related art of investigating a specific person (person to be retrieved) at high speed. However, the tendency of the feature data of the extracted person varies depending on the image pickup condition (lighting, angle of view, orientation and size of person) and thus a threshold value of matching processing (boundary value between the person in question and a different person) must be adjusted by taking into account the photographing condition of each camera at the retrieving time and there is a problem in that it takes time until any desired result is provided. That is, the user must perform repetitive operation such that if the threshold value is set to a low value, erroneous detection increases and if the threshold value is set to a high value, undetected errors increase; efficiency is very poor.
On the other hand, an art of improving the retrieval accuracy using a plurality of feature amounts in combination is proposed as a related art for solving the problem described above (for example, refer to patent document 1, patent document 2, or patent document 3). Patent document 1 describes a technique of managing the feature data of a person in moving image units (time series data units) rather than still image units, thereby suppressing temporary variation of the feature data of the person for improving the retrieval accuracy, and patent document 2 describes a technique of automatically correcting the retrieval condition using a manually given keyword and manually given person feature data in combination. Patent document 3 describes a technique of using RFID (Radio Frequency Identification) and person feature data in combination for improving detection/retrieval accuracy of an unauthorized passerby.    Patent document 1: Japanese Patent Laid-Open No. 2006-178516    Patent document 2: Japanese Patent Laid-Open No. 2005-100090    Patent document 3: Japanese Patent Laid-Open No. 2006-236183